Top of the Screen Banner colours

Is it possible to change the two-tone blue banner at the top of the page?

As I understand it this functionality doesn't currently exist.

We process transactions for three different companies, which must be quite normal for accounting practices providing bookkeeping (or payroll) services or, like us, a small group of companies, and it would be a GREAT VISUAL prompt to see different colour schemes depending on the company/client.

My preference - two-tone Blue for my Employer which is the default setting that I see and I assume everyone else sees. Rhubarb and Custard and two-tone green would work for the other two entities we account for, but if a pallette of colours were available - then users would/could be able to be prompted by a simple visual clue of their choice, that might match separate corporate identities, as to which set of books were being updated.

For accountants who provide bookkeeping services this would help the clerks too.